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目的采用经颅多普勒超声(TCD)分析血管迷走性晕厥(VVS)的脑血流动力学特点,并探讨TCD对VVS的临床应用价值。方法对2011年12月至2013年8月于兰州大学第二医院小儿心血管科就诊的38例血管迷走性晕厥患儿,及20名体检健康儿童行直立倾斜试验,并应用TCD进行监测。结果基础状态下,观察组与对照组比较,左右大脑中动脉的收缩期血流速度(Vs)、舒张末期血流速度(Vd)、平均血流速度(Vm)差异无统计学意义(P>0.05),脉冲指数(PI)值差异无统计学意义(P>0.05);对照组行直立倾斜试验后与基础状态时比较,左右大脑中动脉的Vs、Vd、Vm差异无统计学意义(P>0.05),PI值差异无统计学意义(P>0.05);观察组通过直立倾斜试验诱发血管迷走性晕厥阳性反应时与基础状态时比较,左右大脑中动脉的Vs、Vd、Vm明显加快(P<0.05),PI值明显升高(P<0.05)。结论 VVS发生时,脑血管阻力增加,脑血流调节障碍;TCD检查对于判断VVS患儿脑血流状态具有重要价值。
Objective To analyze the cerebral hemodynamic characteristics of vasovagal syncope (VVS) by transcranial Doppler ultrasound (TCD) and to explore the clinical value of TCD for VVS. Methods Thirty-eight children with vasovagal syncope and 20 healthy children undergoing pediatric cardiology at the Second Hospital of Lanzhou University from December 2011 to August 2013 underwent orthostatic tilt test and monitored by TCD. Results Compared with the control group, there was no significant difference in the systolic velocity (Vs), end-diastolic velocity (Vd) and mean velocity (Vm) of the left and right middle cerebral arteries in the observation group and the control group (P> 0.05). There was no significant difference in pulse index (PI) between the two groups (P> 0.05). There was no significant difference in Vs, Vd and Vm between the left and right middle cerebral arteries in the control group (P> 0.05). There was no significant difference in PI value between the two groups (P> 0.05). Vs, Vd and Vm of the left and right middle cerebral arteries were significantly increased in the observation group when the vasovagal syncope-positive reaction was induced by upright tilt test compared with the basal state P <0.05), PI value increased significantly (P <0.05). Conclusions VVS occurs when cerebral vascular resistance increases and cerebral blood flow regulation is impaired. TCD examination is of great value in judging cerebral blood flow state in children with VVS.